This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP third generation partnership project
DL downlink (eNB to UE)
eNB EUTRAN Node B (evolved Node B/base station)
EUTRAN evolved UTRAN (LTE)
LTE long term evolution
MDT minimization of drive tests
RRC radio resource control
UE user equipment
UL uplink (UE to eNB)
UTRAN universal terrestrial radio access network
In the communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE, E-UTRA or 3.9G), the LTE Release 8 is completed, the LTE Release 9 is being standardized, and the LTE Release 10 is currently under development within the 3GPP. In LTE the downlink access technique is OFDMA, and the uplink access technique is single carrier, frequency division multiple access SC-FDMA, and these access techniques are expected to continue in LTE Release 10.
FIG. 1 shows the overall architecture of the E-UTRAN system. The EUTRAN system includes eNBs, providing the EUTRA user plane and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an evolved packet core, more specifically to a mobility management entity MME and to a serving gateway S-GW. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and the eNBs.
There is a need for the wireless network operator to obtain measurement reports from the DL perspective in order to maintain and optimize network coverage. These are often referred to as drive tests, and networks use them sparingly due to the limited portable power of the mobile devices that collect the DL measurements. This is generally termed as MDT. Further details of drive tests for next generation LTE (generally Release 10 and beyond) may be seen at 3GPP TR 36.805 v9.0.0 (2009-12), which details purposes of drive tests and uses of the parameters that the UEs measure.
Manual drive tests are relatively expensive for the network operators and so consideration is recently given to involving user terminals to automate the underlying data collection function. Currently, in 3GPP there are two MDT reporting approaches: immediate MDT reporting and logged MDT reporting. Immediate MDT reporting means the UE reports the MDT measurements to the eNB immediately when the MDT measurements are taken. Logged MDT reporting means the UE takes its measurements while in the IDLE mode, stores them locally, and reports them when it gets a connection again to the network.
In was agreed in 3GPP that when a UE goes ACTIVE again from an IDLE mode, it will indicate the availability of its locally stored/logged MDT reports to the network. When the network gets this indication, depending on its implementation algorithm it will initiate the UE to report its logged MDT reports to the network. Since the “Availability Indication” simply needs to indicate a binary indication of whether there is or is not logged MDT measurements to report, that availability indication can be as simple as a single bit.
Since logged MDT reporting is not yet well defined, many potential problems are not yet identified.